JPS58115120A - Manufacturing method of pitch carbon fiber - Google Patents

Abstract

PURPOSE:To obtain carbon fibers of high performance, having a low softening point and improved strength, Young's modulus, etc., by using a pitch having a reflectance in a specific range as a raw material. CONSTITUTION:A pitch having 8.5-9.3% minimal value of the reflectance and 11.8-12.5% maximal value thereof is used a raw material and melt spun to give pitch fibers, which are then made infusible in an atmosphere of an oxidizing gas of preferably 20-100% concentration at 20-300 deg.C for 5min-10hr, and heated at 5-20 deg.C/min heating rate to 800-3,500 deg.C in an atmosphere of an inert gas and carbonized or graphitized to afford the aimed carbon fibers. Preferably, a pitch obtained by catalytically cracking petroleum, e.g. kerosene, light oil or residual oil after the atmospheric distillation, and heat-treating the resultant heavy oil having 400-500 deg.C boiling point if necessary under 20-350kg/cm<2>.G pressure of hydrogen is used as the raw material pitch.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an excellent pitch for producing high performance carbon fibers.

In recent years, many methods for producing carbon fiber using pitch as a raw material have been reported. When manufacturing carbon fiber using pitch as a raw material, the elastic modulus of carbon fiber.

It is said that performance such as tensile strength greatly depends on the properties of the raw material pitch. For example,
No. 611 specifies that pitch containing 40 to 90% d-phase is a requirement for producing high-performance carbon fibers. However, in order to obtain a pitch containing 40 to 901% men phase, it is necessary to heat treat the pitch at a temperature of 350° C. or higher for a long period of time, usually about 10 hours. Further, since the softening point of the obtained pitch is usually 300°C or higher, melt spinning must be carried out at a high temperature of 350°C or higher. The higher the softening point of the pitch, the higher the melt-spinning temperature, which is economically disadvantageous.Also, the higher the softening point of the pitch, the higher the melt-spinning temperature, which is economically disadvantageous.However, during the melt-spinning process, thermal deterioration such as an increase in quinolinous solvent and the generation of cracked gas easily occur, making it difficult to use high-performance carbon. It becomes difficult to obtain fiber.

The present invention provides a modified pitch that can be prepared in a relatively short time, has a low softening point, and has excellent properties for producing high-performance carbon fibers. By using it as a raw material, high performance carbon fiber can be produced.

That is, the present invention has a minimum reflectance of 8.5 to 9.3.
and the maximum value is 11.8 to 12. This is a method of manufacturing carbon fiber using pitch having a value within the range of Fl as a raw material.

The reflectance is measured by embedding the sample pitch in a resin such as acrylic resin, polishing it, and using a reflectance measuring device in air. Specifically, at least 100
The above points are arbitrarily selected, the sample is rotated 360 degrees within a plane around the point, and the maximum and minimum values of reflectance at each point are measured. The maximum value among the maximum values and the minimum value among the minimum values are the maximum value and minimum value of the reflectance of the sample pitch.

Thus, only pitches with a minimum value of reflectance measured in the range of 8.5 to 9.3% and a maximum value in the range of 11.8 to 12.5% produce high performance carbon fibers. This can be the optimal pitch. If either the minimum value or the maximum value of the pitch reflectance is outside the range of reflectance values specified in the present invention, the pitch no longer has excellent properties as a pitch for carbon fibers, and the pitch does not have high performance. It is not possible to produce carbon fiber.

There are no particular limitations on the method for preparing the pitch having a specific reflectance of the present invention and the pitch used as a raw material.

As the raw material pitch, carbonaceous pitch such as coal-based pitch and petroleum-based pitch can be used. In particular, it does not contain infusible substances, does not contain mesophase, and has a softening point of 50 to 200.
A pitch of °C is preferred.

Examples of pitches suitable as raw materials include: (1) When producing olefins such as ethylene and propylene by steam cracking petroleum such as naphtha, kerosene or light oil, usually at 700 to 1200°C. heavy oil with a substantially boiling point range of 200 to 450°C as a by-product of
By fluid catalytic cracking of petroleum such as light oil or atmospheric residual oil in the presence of natural or synthetic silica/alumina catalyst or zeolide catalyst at 450 to 550°C and normal pressure to 20 kg/cm-G, Substantially the boiling point range of 200 to 450 is a by-product produced when producing light oil such as gasoline.
℃ heavy oil, (3) 2 rings or 33 parts per 100 parts by volume of the heavy oil in (1) above 10 to 200 parts by volume of aromatic hydrocarbon nuclear hydride are added, and the temperature is 370 to
Pitch obtained by heat treatment at 480°C and pressure 2 to 50 9/cm/G, (4) Heavy oil 1 of (2) above
00 parts by volume, add 10 to 200 parts by volume of a nuclear hydride of 21jI or 3-ring aromatic hydrocarbon, temperature 37.0 to 480'C, pressure 2 to 50 kg/crn2.
Pitch obtained by heat treatment at G, (5) (1)
) Pitch obtained by heat treating the heavy oil of (2) above under hydrogen pressure of 20 to 350 kg/cm2・G at a temperature of 400 to 500°C; Yu/cW
Pitch obtained by heat treatment at a temperature of 400 to 500°C under L2.G hydrogen pressure, (7) When petroleum is steam cracked for 100 parts by volume of the heavy oil of (1) above. Obtained boiling point range 160-4
The heavy oil with a boiling point of 200°C or more obtained when steam cracking of 0'O℃ fraction and /''! or petroleum is heated to a temperature of 37°C.
Boiling point range 16 produced when heat treated at 0 to 480°C
Hydrogen obtained by contacting a 0-400°C fraction with hydrogen in the presence of a hydrogenation catalyst and hydrogenating 10-70% of the aromatic nuclei of aromatic hydrocarbons contained in the fraction. Chemical oil 10
Pitch obtained by adding ~200 parts by volume and heat-treating at a temperature of 370 to 4PO℃ and a pressure of 2 to 50 kg/Tan2.G, (8) the heavy oil of (1) above and the heavy oil of (2) above; A mixed oil of heavy oil and the hydrogenated oil of (7) above (the mixing ratio is by weight, heavy oil of above (1): heavy oil of above (2) is 1:0
, 1 to 9, and the total amount of the heavy oil of (1) and the heavy oil of (2): the hydrogenated oil of (7) is 1:"0.1 to 2
) at a temperature of 370°C to 480°C and a pressure of 2 to 50k.
g/cm2. Pitch obtained by heat treatment in G.
, (4), (6), (7), and (8) pitches are preferred.

2-ring or 33 used in (3) and (4) above
Nuclear hydrides of aromatic hydrocarbons in No. 31 are nuclear hydrides of naphthalene, indene, biphenyl, acenaphthylene, anthracene, phenanthrene, and alkyl substituted products having 1 to 3 carbon atoms.

Specifically, decalin, methyldecalin, tetralin,
Methyltetraline, dimethyltetraline, ethyltetraline, isopropyltetraline, indane, decahydrobiphenyl, acenaphthene, methylacenaphthene, tetrahydroacenaphthene, dihydroanthracene, methylhydroanthracene, dimethylhydroanthracene, ethylhydroanthracene, tetrahydroanthracene ,
Hexahydroanthracene, octahydroanthracene, dodecahydroanthracene, tetradecahydroanthracene, dihydrophenanthrene, methyldihydrophenanthrene, tetrahydrophenanthrene, hexahydrophenanthrene, octahydrophenanthrene, dodeca Mention may be made of hydrophenanthrene and tetradehydrophenanthrene. Especially 2.1! or 3
Nuclear hydrides of condensed cyclic aromatic hydrocarbons are preferred. Moreover, these can also be used as a mixture of two or more types.

The preparation method is not specified either, but for example, the raw material pitch is melted in an inert gas atmosphere to form a liquid, and this liquid pitch is preferably formed into a thin film with a thickness of 5 sm or less. 350℃・preferably 250℃
At a temperature of ~345°C, under reduced pressure, preferably Oll ~
1-30 minutes under reduced pressure of 10 mHH, preferably 5-2
Process for 0 minutes. Further, 300 to 450
°C, preferably at a temperature of 350-400 °C for 1-60 minutes,
An example of a method is preferably heat treatment for 5 to 40 minutes. Through such processing, the minimum value of the pitch reflectance is 8.5 to 9.3 inches, and the maximum value is 11.
It is made to have a value within the range of 8 to 12.5%.

The pitch having a specific reflectance of the present invention is melt-spun into pitch fibers according to a conventional method, and then subjected to an infusible treatment,
Subsequently, it is carbonized or further graphitized to produce carbon fibers with high elastic modulus and high strength.

The conditions for melt spinning are usually to set the spinning temperature to about 40 to 70°C higher than the softening point of the pitch, and to obtain a diameter of 0.1°C.
Extrusion from ~0.5 nozzle, 200~2000m
Wind up at a winding speed of /minute.

The pitch fibers obtained by melt spinning are then 20 to 10
Infusibility treatment is performed in an oxidizing gas atmosphere of 0% concentration. Oxidizing gases usually include oxygen, ozone, air,
Oxidizing gases such as nitrogen source compounds, halogens, and sulfur dioxide gases are
A species or two or more species are used. This infusibility treatment is carried out under temperature conditions in which the melt-spun pitch fibers, which are the objects to be treated, are not softened or deformed. For example, a temperature of 20 to 360°C, preferably 20 to 300°C is employed. Moreover, the processing time is usually 5 minutes to 10 hours.

The infusible pitch fibers are then carbonized or further graphitized in an inert gas atmosphere to obtain carbon fibers.

The conditions at this time are that the temperature is raised to a rate of 5-3500° C. in an inert gas atmosphere and held for 1 second to 1 hour.

The present invention will be specifically explained below using Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 Gas oil was heated to 1 kg/c at 500°C in the presence of a zeolite catalyst.
Boiling point 200℃ of by-product generated during fluid catalytic cracking at m2G
Heavy oil (A) (properties shown in Table 1) 150+n
In an autoclave with a stirrer and an internal volume of 300 m1, the initial pressure of hydrogen was 100, 9/cfn2・G, and the heating rate was 3°C/G.
The mixture was heated to 430°C for 3 hours and held at 430°C for 3 hours. Thereafter, heating was stopped and the mixture was cooled to room temperature. The obtained liquid product was distilled at 250°C/1■Hg to remove light components, which had a softening point of 68°C.

(1) was obtained.

Next, pitch (1) was heated at 345°C under a reduced pressure of 1ttmHg.
After treatment with a film evaporator for 15 minutes at
Pitch (2) at 5°C was obtained. When the reflectance of this pitch (2) was measured using a reflectance measuring device manufactured by Rhine, the maximum value was 12.0% and the minimum value was 8.8%.

This pitch (2) is set to a nozzle diameter of 0.3 teeth and L/D=1.
Melt-spun the fibers using a spinning machine at a spinning temperature of 310°C and a winding speed of 800W to obtain 12μ pitch fibers, which were then subjected to infusibility, carbonization and graphitization treatments under the conditions shown below to obtain carbon fibers. Ta.

The processing conditions for infusibility, carbonization and graphitization are as follows.

Infusibility conditions: Heating in air atmosphere at a heating rate of 1°C/min to 300°C. Hold at 300°C for 30 minutes.

Carbonization conditions: In nitrogen atmosphere, temperature increased at 10℃/min to 1000℃
Hold at ℃ for 30 minutes.

Graphitization conditions: Heat treatment to 2000°C at a heating rate of 50°C/min in an argon stream and hold for 1 minute.

The diameter of the obtained carbon fiber was 11μ, and the tensile strength was 23
．． Table 1 Properties of heavy oil condensate Salt 1 mouth 11 Pitch (1) of Example 1, Pitch (1) 119, Nitrogen 2 ml 7 The mixture was stirred with ventilation for 6 hours and heat treated at a temperature of 400°C for 6 hours to obtain pitch (3) with a softening point of 263°C. When the reflectance of this pitch (3) was measured, the maximum value was 12.4 inches. The minimum value is 8.4%
Met.

When this pitch (3) was melt-spun using the spinning machine used in Example 1 at a spinning temperature of 320° C. and a winding speed of 800 m/min, uniform spinning could not be achieved.

Example 2 Boiling point 2 produced as a by-product when naphtha was steam decomposed at 830°C
Heavy oil with a temperature of 00°C or higher) was collected. The properties of this heavy oil Φ) are shown in Table fa2. Next, the heavy oil (B) was heated to a pressure of 15
12.G1 Heat treatment was performed at a temperature of 400° C. for 3 hours. This heat-treated oil (0) was distilled at 250°C/1.Ovm Hg, and a fraction (b) with a boiling point of 160 to 400°C was collected.

Its properties are shown in Table 3. This fraction (b) was treated at a pressure of 35% using a nickel-molybdenum catalyst (NM-502).
kg7cm -G, temperature 330℃, space velocity (LH
8V) Partial nuclear hydrogenation was carried out by contacting with hydrogen at 1.5 to obtain hydrogenated oil (8).The nuclear hydrogenation rate was 31 〇 50 parts by volume of the above-mentioned heavy oil (B) Hydrogenated oil (g) 5
0 parts by volume were mixed and heat treated at a pressure of 2012 G and a temperature of 430° C. for 3 hours. This heat treated oil was heated at 250℃/1.
Distilled at 0 mHg to remove light components, softening point 100
℃ pitch (4) was obtained.

Next, the pitch (4) was heated at 345°C under a reduced pressure of ]mHg.
After 5 minutes of heat treatment in a lume evaporator, heat treatment was performed at 380°C for 30 minutes under normal pressure to achieve a softening point of 232°C.
pitch (5) was obtained. When the reflectance of this pitch (5) was measured, the maximum value was 12.3%, and the minimum value was 9.
It was 1%.

This pitch (5) was melt-spun using the spinning machine used in Example 1 at a spinning temperature of 315°C and a winding speed of 800 ml to obtain a pitch fiber of 13μ. Melting, carbonization, and graphitization were performed.

The diameter of the obtained carbon fiber was 11μ, and the tensile strength of the bow was 2.
20 kg/am2, Young's modulus is 24 Ton/g2
Table 2 Properties of heavy oil (B) Table 3 Properties of fraction (G) Comparative example 2 Pitch (4) of Example 2 was changed to pitch (4) of 1.9, nitrogen was 2 ml was stirred for 7 minutes with ventilation and heat treated at a temperature of 4.00°C for 12 hours to obtain pitch (6) with a softening point of 301°C. When the reflectance of this pitch (6) was measured, the maximum value was 13.3, and the minimum value was 9.1.
%Met.

When this pitch (6) was melt-spun using the spinning machine used in Example 1 at a spinning temperature of 355°C and a winding speed of 800 m/min, the pitch (6) was thermally altered and continuous spinning was impossible. there were.

Example 3 60 parts by weight of the heavy oil used in Example 1, 30 parts by weight of the heavy oil used in Example 2 and 10 parts by weight of hydrogenated oil
Parts by weight were mixed and heat treated at a pressure of 20 kg 7 cm 2 -G and a temperature of 430° C. for 3 hours. 25% of this heat treated oil
0℃'/1. The light components were distilled using Omug to obtain pitch (7) with a softening point of 80°C.

Next, the pitch (7) was heated at 345°C under a reduced pressure of 1 mHH.
After processing in a film evaporator for 5 minutes, heat treatment was performed for 20 minutes at 37o"c under normal pressure to reach a softening point of 26i.
T? : Pitch (8) was obtained. The maximum value of the reflectance for this pitch (8) was 12.4%, and the minimum value was 9.0.

This pitch (8) was melt-spun using the spinning machine used in Example 1 at a spinning temperature of 320°C and a winding speed of 780 ml to obtain a pitch fiber of 12μ. Melting, carbonization, and graphitization were performed.

The diameter of the obtained carbon fiber was 10μ, and the tensile strength was 22
0 kll/wa2, Young's modulus was 23 Ton/m2.

Comparative Example 3 The pitch (7) of Example 3 was changed to 4 under a reduced pressure of 1 tamHg.
001:: was processed for 10 hours to obtain pitch (9) with an intensification point of 299°C. The maximum value of the reflectance of this pitch (9) was 13.2% and the minimum value was 9.0%. .

This pitch (9) was melt-spun using the same spinning machine used in Example 1 at 360°C and a winding speed of 78 (1 m 1 min), but pitch (9) was thermally altered and continuous spinning was impossible. Met.

Patent applicant: Nippon Oil Co., Ltd. Representative Patent Attorney Tatsuo Ito Tetsuya Ito

Claims (1)

[Claims] The minimum value of reflectance is 8.5 to 9.3 inches, and the maximum value is 11.
A method of producing carbon fiber using pitch having a value within the range of 8 to 12.5% as a raw material.